* [Diagnostics] Use DeclDescriptiveKind on data flow diagnostics to improve diagnostic message
* [tests] Add regression tests to SILOptimizer/return.swift
* [tests] Adapt other tests to changes of SR-14505
* [Diagnostics] Adapt message for missing return diagnostics, remove article
* [Diagnostics] Adapt message for missing return diagnostics to have a note with fix
* [tests] Adjust tests in validation suit